After years of hard working, LED products have been widely spread over the world. At beginning, the cost of LED products is too high, preventing LED products to be popular. Nowadays, LED product price has lowered to an acceptable level.
However, it is always important to further find every aspect to improve such devices, particularly for such worldwide products related to human daily life. Heat efficiency, color rendering index, and more characteristics need to consider when designing LED devices.
In the present invention, inventors look deeper into the LED basic structure and finds several inventive points to further improve LED device performance.